Hydrogen storage assembly

ABSTRACT

A hydrogen storage assembly includes at least one wafer formed of a substrate material that produces metal hydride when exposed to a hydrogen-rich carrier fluid. The wafer can be supported by a housing and arranged so that the hydrogen-rich carrier fluid can flow over a reaction surface of the wafer. At least one heating element can be arranged to transfer heat to the wafer to attain an operating temperature suitable for hydrogen charging on the reaction surface. A de-activation material may be provided on the reaction surface for inhibiting formation of surface oxide that impedes hydrogen absorption during charging and hydrogen desorption during discharging. The at least one wafer can include a plurality of monolithic plate wafers spaced apart about a central axis of the assembly. The at least one wafer can include a plurality of monolithic disc wafers in at least one stacked arrangement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 16/060,084 filed onJun. 7, 2018, which is a national stage application of InternationalApplication No. PCT/CA2016/051432 filed on Dec. 7, 2016, which claimspriority to U.S. Provisional Application No. 62/264,051 filed on Dec. 7,2015, and the entire contents of each are hereby incorporated herein byreference.

FIELD

The present disclosure relates generally to hydrogen storage and metalhydride technology.

BACKGROUND

The following paragraphs are not an admission that anything discussed inthem is prior art or part of the knowledge of persons skilled in theart.

The continuously growing demand in energy is causing the depletion ofexisting non-renewable fossil-based energy sources, the use of whichraises serious environmental questions. To overcome this limitedresource and abate greenhouse gas emissions that contribute to climatechange, hydrogen energy technologies can provide the next generationenergy source. The technology for hydrogen-based energy sourcesgenerally requires: (i) clean, renewable and economical processes toproduce pure, high-quality hydrogen; (ii) developing high densitystorage media for hydrogen; and (iii) efficient infrastructures fordelivery and supply chain of hydrogen-based energy technologies.

Metal hydrides, such as MgH₂, NaAlH₄, LiAlH₄, LiH, LaNi₅H₆, TiFeH₂ andpalladium hydride, with varying degrees of efficiency, can be used as astorage medium for hydrogen. Metal hydrides can provide high packingdensity for hydrogen storage, and also can provide for storage in arelatively safe state compared to a high-pressure compressed gaseousform. Conversion of hydrogen (a chemical state) to a workable form ofenergy (e.g., electrical or mechanical) can be carried out by fuelcells, which exist presently to power cars, buses, electrical powergenerators, and the like. To date, there has been research focused onpowder-based materials to develop metal-hydride systems that can storeand release hydrogen in large quantities, efficiently and at lowtemperatures.

INTRODUCTION

The following is intended to introduce the reader to the detaileddescription that follows and not to define or limit the claimed subjectmatter.

In an aspect of the present disclosure, a hydrogen storage assembly isdescribed. The hydrogen storage assembly can include: a housing; atleast one wafer formed of a substrate material that produces metalhydride when exposed to a hydrogen-rich carrier fluid, the at least onewafer supported by the housing and arranged so that the hydrogen-richcarrier fluid can flow over a reaction surface of the at least onewafer; and at least one heating element arranged to transfer heat to theat least one wafer to attain an operating temperature suitable forhydrogen charging on the reaction surface.

The hydrogen storage assembly can include a de-activation material onthe reaction surface for inhibiting formation of surface oxide thatimpedes hydrogen absorption during charging and hydrogen desorptionduring discharging. The substrate material can be a magnesium-basedalloy, and the de-activation material can be a layer of nickel depositedon the reaction surface. The layer of nickel can have a thickness ofbetween 0.5 and 1.5 μm, or about 1 μm. The layer of nickel can have asurface roughness of about 1 μm R_(a) or less.

The at least one wafer can include a plurality of monolithic platewafers spaced apart about a central axis of the assembly. Each of theplate wafers can be suspended generally radially between respectiveinner and outer supports of the housing. Opposing edges of each of theplate wafers can be received in an outwardly facing groove of therespective inner support and an inwardly facing groove of the respectiveouter support.

A central electrical busbar can be supported by the housing andpositioned generally along the central axis, and the at least oneheating element can consist of a plurality of electrical heatingelements connected to and spaced about the central electrical busbar.Each of the electrical heating elements can be received in a respectivesleeve and positioned between the reaction surfaces of adjacent ones ofthe plate wafers to heat the plate wafers by thermal radiation. Each ofthe electrical heating elements can be generally equidistant between thereaction surfaces of the adjacent ones of the plate wafers.

The housing can include at least one sidewall and at least one end cap,each having passages permitting flow of the hydrogen-rich carrier fluidover the plate wafers. The at least one sidewall and at least one endcap can define a top profile of the hydrogen storage assembly that isgenerally round or hexagonal in shape.

The at least one wafer can include a plurality of monolithic disc wafersin at least one stacked arrangement. The housing can include first andsecond end panels, and the disc wafers can be clamped between the endpanels. The end panels can have passages permitting flow of thehydrogen-rich carrier fluid over the disc wafers. Each of the discwafers can include a central hole, and the housing can include at leastone stem that extends through the central holes of the disc wafersbetween the end panels. Disc wafers can be provided in first and secondstacked arrangements, with disc wafers of the first stacked arrangementin contact with disc wafers of the second stacked arrangement so as topermit thermal conduction between the first and second stackedarrangements. The disc wafers of the first stacked arrangement canpartially overlap the disc wafers of the second stacked arrangement instaggered relation. The at least one heating element can include anelectrical heating element received in a central bore of the at leastone stem to heat the disc wafers by thermal conduction. The housing caninclude a plurality of support rods connecting the end panels. The endpanels can define a top profile of the hydrogen storage assembly that isgenerally square or rectangular in shape.

A hydrogen storage system can include a plurality of the hydrogenstorage assemblies.

In an aspect of the present disclosure, a method of storing hydrogen isdescribed. The method can include: providing a hydrogen storage assemblyincluding a plurality of wafers formed of a substrate material thatproduces metal hydride when exposed to a hydrogen-rich carrier fluid,the plurality of wafers each including a reaction surface and ade-activation material on the reaction surface; transferring heat to theplurality of wafers to attain an operating temperature suitable forhydrogen charging on the reaction surfaces; and flowing thehydrogen-rich carrier fluid over the plurality of wafers so as to chargehydrogen on the reaction surfaces, thereby storing hydrogen in thehydrogen storage assembly.

The de-activation material on the reaction surfaces can inhibitformation of surface oxide that impedes hydrogen absorption duringcharging and hydrogen desorption during discharging. The substratematerial can be a magnesium-based alloy, and the de-activation materialcan be a layer of nickel deposited on the reaction surfaces.

The method can include maintaining the operating temperature at about250° C. or less. The step of flowing can include delivering thehydrogen-rich carrier fluid to the at least one wafer at an exposurepressure of about 10 Torr or less.

The method can include, after the step of flowing, flowing a secondcarrier fluid over the plurality of wafers to discharge hydrogen fromthe reaction surfaces, thereby releasing hydrogen from the hydrogenstorage assembly.

The step of heating can include heating the plurality of wafers with atleast one electrical heating element.

The step of heating can include heating the plurality of wafers bythermal radiation. The plurality of wafers can include a plurality ofmonolithic plate wafers, and the method can further include arrangingthe at least one electrical heating element between adjacent ones of theplate wafers.

The step of heating can include heating the plurality of wafers bythermal conduction. The plurality of wafers can include a plurality ofmonolithic disc wafers in at least one stacked arrangement, with each ofthe disc wafers including a central hole, and the method can furtherinclude arranging the at least one electrical heating element extendingthrough the central holes of at least a portion of the disc wafers.

In an aspect of the present disclosure, a wafer for a hydrogen storageassembly is described. The wafer can be formed of a substrate materialthat produces metal hydride when exposed to a hydrogen-rich carrierfluid, and the wafer can include a reaction surface and a de-activationmaterial on the reaction surface for inhibiting formation of surfaceoxide that impedes hydrogen absorption during charging and hydrogendesorption during discharging.

The substrate material can be a magnesium-based alloy, and thede-activation material can be a layer of nickel deposited on thereaction surface. The layer of nickel can have a thickness of between0.5 and 1.5 μm, or about 1 μm. The layer of nickel can have a surfaceroughness of about 1 μm R_(a) or less.

In an aspect of the present disclosure, a method of preparing a waferfor a hydrogen storage assembly is described. The method can include:providing a substrate material that produces metal hydride when exposedto a hydrogen-rich carrier fluid; and depositing a de-activationmaterial on the substrate material to inhibit formation of surface oxidethat can impede hydrogen absorption during charging and hydrogendesorption during discharging.

The substrate material can be a magnesium-based alloy, and the step ofdepositing can include electrodepositing a layer of nickel as thede-activation material. The step of depositing can includeelectrodepositing the layer of nickel to a thickness of between 0.5 and1.5 μm, or about 1 μm. After the step of depositing, the layer of nickelcan have a surface roughness of about 1 μm R_(a) or less.

Other aspects and features of the teachings disclosed herein will becomeapparent, to those ordinarily skilled in the art, upon review of thefollowing description of the specific examples of the presentdisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings included herewith are for illustrating various examples ofapparatuses and methods of the present disclosure and are not intendedto limit the scope of what is taught in any way. In the drawings:

FIG. 1 is a perspective view of a hydrogen storage assembly inaccordance with a first example;

FIG. 2 is a partial cutaway perspective view of the hydrogen storageassembly of FIG. 1;

FIG. 3 is a partial cutaway top view of the hydrogen storage assembly ofFIG. 1;

FIG. 4 is an exploded view of the hydrogen storage assembly of FIG. 1;

FIG. 5 is a perspective view of a plurality of the hydrogen storageassembly of FIG. 1 arranged in a system;

FIG. 6 is a top view of the storage system of FIG. 5;

FIG. 7 is a perspective view of a hydrogen storage assembly inaccordance with a second example;

FIG. 8 is a partial cutaway perspective view of the hydrogen storageassembly of FIG. 7;

FIG. 9 is a partial cutaway top view of the hydrogen storage assembly ofFIG. 7;

FIG. 10 is an exploded view of the hydrogen storage assembly of FIG. 7;

FIG. 11 is a perspective view of a plurality of the hydrogen storageassembly of FIG. 7 arranged in a system;

FIG. 12 is a top view of the storage system of FIG. 11;

FIG. 13 is a perspective view of a hydrogen storage assembly inaccordance with a third example;

FIG. 14 is a partial cutaway perspective view of the hydrogen storageassembly of FIG. 13;

FIG. 15 is an exploded view of the hydrogen storage assembly of FIG. 13;

FIG. 16 is a perspective view of a plurality of the hydrogen storageassembly of FIG. 13 arranged in a system; and

FIG. 17 is a top view of the storage system of FIG. 16.

DETAILED DESCRIPTION

Various apparatuses or methods will be described below to provide anexample of an embodiment of each claimed invention. No embodimentdescribed below limits any claimed invention and any claimed inventionmay cover apparatuses and methods that differ from those describedbelow. The claimed inventions are not limited to apparatuses and methodshaving all of the features of any one apparatus or method describedbelow, or to features common to multiple or all of the apparatuses ormethods described below. It is possible that an apparatus or methoddescribed below is not an embodiment of any claimed invention. Anyinvention disclosed in an apparatus or method described below that isnot claimed in this document may be the subject matter of anotherprotective instrument, for example, a continuing patent application, andthe applicant(s), inventor(s) and/or owner(s) do not intend to abandon,disclaim or dedicate to the public any such invention by its disclosurein this document.

The present disclosure relates to the use of a wafer-based media thatallows for relatively high density hydrogen storage and releasecapabilities, and at relatively low temperatures and pressures,generally without having to use powder metallurgy, glove-box technologyand/or other expensive equipment for hydrogen charging and discharging.

Referring to FIGS. 1 and 2, an example of a first hydrogen storageassembly is shown generally at reference numeral 100. In the exampleillustrated, the assembly 100 includes a housing 102 having a main body104 and an upper end cap 106.

In the example illustrated, the main body 104 includes side walls 108and a bottom wall 110. The main body 104 is shown to include passages112 between the side walls 108 and passages 114 between the bottom wall110, and the end cap 106 is shown to include passages 116. The passages112, 114, 116 can permit a carrier fluid to flow in to and out from theassembly 100.

Referring to FIGS. 3 and 4, the assembly 100 includes wafers 118 thatare formed of a substrate material that produces metal hydride whenexposed to a hydrogen-rich carrier fluid. The wafers 118 are supportedby the housing 102 and arranged so that the carrier fluid can flow overa reaction surface 120 of the wafers 118. In some examples, the metalhydride producing substrate material can be a magnesium-based alloy.Other metal hydride producing materials are possible, including, forexample but not limited to, Zr—V, Ti—Fe and/or Ti—V alloys.

In some examples, the wafers 118 can include a de-activation material onthe reaction surface 120. The de-activation material can inhibitformation of surface oxide that can impede hydrogen absorption duringcharging and hydrogen desorption during discharging, which can bereferred to as a “poisoning” effect that can occur during repeated useof the wafers 118. In some examples, the de-activation material can be alayer of nickel deposited on the reaction surface 120. The layer ofnickel can be electrodeposited and have a thickness of between 0.5 and1.5 μm, or about 1 μm. The layer of nickel can have a smooth surfacefinish, e.g., a surface roughness of about 1 μm R_(a) or less.

In the example illustrated, the assembly 100 includes heating elements122 supported by the housing 102. The heating elements 122 are arrangedto transfer heat to the wafers 118 to attain an operating temperaturesuitable for hydrogen charging on the reaction surfaces 120. In someexamples, the operating temperature can be between about 200 and 250° C.

In the example illustrated, there are eight sets of two parallel wafers118 in an octagonal array, held in the housing 102 that is shapedgenerally as a cylinder. As illustrated, each of the wafers 118 can be aflat plate that is thin-walled, monolithic or solid, rectangular inshape, and spaced apart about a central axis 124 of the assembly 100. Insome examples, the wafers 118 can have dimensions of about 75×20×0.5 mm(length, width, thickness, respectively). Other configurations anddimensions are possible.

In the example illustrated, each of the wafers 118 is suspendedgenerally radially about the central axis 124 between inner supports 126and outer supports, which in the example illustrated are formed by theside walls 108. Each of the wafers 118 are shown having an inner edgereceived in an outwardly facing groove 128 of the respective innersupport 126, and an outer edge received in an inwardly facing groove 130of the respective side wall 108.

Referring again to FIG. 2, the assembly 100 includes a centralelectrical busbar 132 supported by the housing and positioned generallyalong the central axis 124 (FIG. 4). In the example illustrated, thebusbar 132 is shown to include longitudinal ridges 134 defining outwardfaces 136. Electrical power can be provided to the busbar 132 via atleast one set of terminals 138.

Referring to FIGS. 2, 3 and 4, the heating elements 122 are connected toand spaced about the busbar 132. In the example illustrated, there are atotal of sixteen of the wafers 118 and eight of the heating elements122. Each of the heating elements 122 is shown received in a respectivesleeve 140 and positioned between the reaction surfaces 120 of adjacentones of the wafers 118 to heat the wafers 118 by thermal radiation. Thesleeves 140 can serve to keep the heating elements 122 from contactingthe wafers 118. The sleeves 140 can be made of glass or anothertransparent or translucent material to allow transmission of radiantheat to the wafers 118. As shown, the reaction surfaces 120 of adjacentpairs of the wafers 118 can be generally parallel to one another, andthe heating element 122 can be approximately equidistant to both of thereaction surfaces 120, which can promote uniform heating of the wafers118.

In the example illustrated, each of the heating elements 122 can takethe form of a flat ribbon with a serpentine shape for increasing itselectrical resistance and increasing surface area for radiation to thereaction surfaces 120. In the example illustrated, each of the heatingelements 122 includes connector mounts 142 at its ends, and the mounts142 mate with the outward faces 136 of the busbar 132 to establish anelectrical connection therewith.

In the example illustrated, the sleeves 140 have a T-shaped profilealong the inward edges, which are received in a corresponding T-shapedslot in the respective inner support 126. In the example illustrated,outward edges of the sleeves 140 are received in an inwardly facinggroove 144 on the side wall 108. In the example illustrated, in each ofthe side walls 108 there is a single groove 144 disposed intermediate oftwo of the grooves 130.

Referring to FIGS. 5 and 6, several of the assembly 100 can be arrangedtogether to create a hydrogen storage system 150. The housing of theassembly 100 defines at top profile that is generally round in shape,thereby permitting fluid flow around the assemblies in the system 150.

Referring to FIGS. 7 and 8, an example of a second hydrogen storageassembly is shown generally at reference numeral 200. In the exampleillustrated, the assembly 200 includes a housing 202 having a main body204 and an upper end cap 206.

In the example illustrated, the main body 204 includes side walls 208and a bottom wall 210. The main body 204 is shown to include passages212 between the side walls 208 and passages 214 between the bottom wall210, and the end cap 206 is shown to include passages 216. The passages212, 214, 216 can permit a carrier fluid to flow in to and out from theassembly 200.

Referring to FIGS. 9 and 10, the assembly 200 includes wafers 218 thatare formed of a substrate material that produces metal hydride whenexposed to a hydrogen-rich carrier fluid. The wafers 218 are supportedby the housing 202 and arranged so that the carrier fluid can flow overa reaction surface 220 of the wafers 218. In some examples, the metalhydride producing substrate material can be a magnesium-based alloy.Other metal hydride producing materials are possible.

In some examples, the wafers 218 can include a de-activation material onthe reaction surface 220. The de-activation material can inhibitformation of surface oxide that can impede hydrogen absorption duringcharging and hydrogen desorption during discharging, which can bereferred to as a “poisoning” effect that can occur during repeated useof the wafers 218. In some examples, the de-activation material can be alayer of nickel deposited on the reaction surface 220. The layer ofnickel can be electrodeposited and have a thickness of between 0.5 and1.5 μm, or about 1 μm. The layer of nickel can have a smooth surfacefinish, e.g., a surface roughness of about 1 μm R_(a) or less.

In the example illustrated, the assembly 200 includes heating elements222 supported by the housing 202. The heating elements 222 are arrangedto transfer heat to the wafers 218 to attain an operating temperaturesuitable for hydrogen charging on the reaction surfaces 220. In someexamples, the operating temperature can be between about 200 and 250° C.

In the example illustrated, there are six sets of three parallel wafers218 in a hexagonal array, held in the housing 202 that is shapedgenerally as a hexagonal prism. As illustrated, each of the wafers 218can be a flat plate that is thin-walled, monolithic or solid,rectangular in shape, and spaced apart about a central axis 224 of theassembly 200. In some examples, the wafers 218 can have dimensions ofabout 75×20×0.5 mm (length, width, thickness, respectively). Otherconfigurations and dimensions are possible.

In the example illustrated, the wafers 218 each of the wafers 218 issuspended generally radially about the central axis 224 between innersupports 226 and outer supports, which in the example illustrated areformed by the side walls 208. Each of the wafers 218 are shown having aninner edge received in an outwardly facing groove 228 of the respectiveinner support 226, and an outer edge received in an inwardly facinggroove 230 of the respective side wall 208.

Referring again to FIG. 8, the assembly 200 includes a centralelectrical busbar 232 supported by the housing and positioned generallyalong the central axis 224 (FIG. 9). In the example illustrated, thebusbar 232 is shown to include outward faces 236. Electrical power canbe provided to the busbar 232 via at least one set of terminals 238.

Referring to FIGS. 8, 9 and 10, the heating elements 222 are connectedto and spaced about the busbar 232. In the example illustrated, thereare a total of eighteen of the wafers 218 and twelve of the heatingelements 222. Each of the heating elements 222 is shown received in arespective sleeve 240 and positioned between the reaction surfaces 220of adjacent ones of the wafers 218 to heat the wafers 218 by thermalradiation. The sleeves 240 can serve to keep the heating elements 222from contacting the wafers 218. The sleeves 240 can be made of glass oranother transparent or translucent material to allow transmission ofradiant heat to the wafers 218. As shown, the reaction surfaces 220 ofadjacent pairs of the wafers 218 can be generally parallel to oneanother, and the heating element 222 can be approximately equidistant toboth of the reaction surfaces 220, which can promote uniform heating ofthe wafers 218.

In the example illustrated, each of the heating elements 222 can takethe form of a flat ribbon with a serpentine shape for increasing itselectrical resistance and increasing surface area for radiation to thereaction surfaces 220. In the example illustrated, each of the heatingelements 222 includes connector mounts at its ends, and the mounts matewith the outward faces 236 of the busbar 232 to establish an electricalconnection therewith.

In the example illustrated, the sleeves 240 have inward edges that arereceived in a slot in the respective inner support 226. In the exampleillustrated, outward edges of the sleeves 240 are spaced apart from theside wall 208.

Referring to FIGS. 11 and 12, several of the assembly 200 can bearranged together to create a hydrogen storage system 250. The housingof the assembly 200 defines at top profile that is generally hexagonalin shape, thereby enabling a relatively close-packed arrangement.

Referring to FIGS. 13 and 14, an example of a third hydrogen storageassembly is shown generally at reference numeral 300. In the exampleillustrated, the assembly 300 includes a housing 302 having a first endpanel 304 and a second end panel 306 spaced apart from the first endpanel 304.

In the example illustrated, the housing 302 includes support rods 308and stems 310 extending between and connecting the end panels 304, 306.The end panels 304, 306 are shown to include passages 314, 316,respectively. The passages 314, 316 and spacing around the support rods308 can permit a carrier fluid to flow in to and out from the assembly300.

Referring to FIGS. 14 and 15, the assembly 300 includes wafers 318 thatare formed of a substrate material that produces metal hydride whenexposed to a hydrogen-rich carrier fluid. The wafers 318 are supportedby the housing 302 and arranged so that the carrier fluid can flow overa reaction surface of the wafers 318. In some examples, the metalhydride producing substrate material can be a magnesium-based alloy.Other metal hydride producing materials are possible.

In some examples, the wafers 318 can include a de-activation material onthe reaction surface. The de-activation material can inhibit formationof surface oxide that can impede hydrogen absorption during charging andhydrogen desorption during discharging, which can be referred to as a“poisoning” effect that can occur during repeated use of the wafers 318.In some examples, the de-activation material can be a layer of nickeldeposited on the reaction surface. The layer of nickel can beelectrodeposited and have a thickness of between 0.5 and 1.5 μm, orabout 1 μm. The layer of nickel can have a smooth surface finish, e.g.,a surface roughness of about 1 μm R_(a) or less.

In the example illustrated, the assembly 300 includes heating elements322 supported by the housing 302. The heating elements 322 are arrangedto transfer heat to the wafers 318 to attain an operating temperaturesuitable for hydrogen charging on the reaction surfaces. In someexamples, the operating temperature can be between about 200 and 250° C.

In the example illustrated, there are four sets of the wafers 318 in astacked arrangement in a square array, held in the housing 302 that isshaped generally as a cuboid. As illustrated, each of the wafers 318 canbe a flat disc that is thin-walled, monolithic or solid, and annular inshape. In some examples, the wafers 318 can have dimensions of about12.5×45×0.5 mm (inside diameter, outside diameter, thickness,respectively). Other configurations and dimensions are possible.

In the example illustrated, each of the wafers 318 includes a centralhole, and a respective one of the stems 310 extends through the centralhole. Hardware 344 applied to the support rods 308 and the stems 310 canexert a clamping force to clamp the wafers 318 between the end panels304, 306. The number of the wafers 318 stacked between the end panels304, 306 can be varied to vary the overall size of the assembly 300.

In the example illustrated, the heating elements 322 are received withina central bore of each of the stems 310 to heat the wafers 318 bythermal conduction. Each of the heating elements 322 can take the formof a hermetically-sealed cartridge heater, and electrical power can beprovided to the heating elements 322 via terminals 338.

In the example illustrated, the wafers 318 are provided in four stackedarrangements, and contact between them can permit thermal conductionbetween all of the stacks. In the example illustrated, the wafers 318 ofone stack partially overlap the wafers 318 of two adjacent stacks, in analternating or staggered relationship with each, but does not overlapthe wafers 318 of the stack that is diagonally opposite and of mirroredformation. With two of the stacks staggered relative to the other twostacks of the wafers 318, the utilization of space can be enhanced so asto reduce the overall dimensions of the assembly 300.

Referring to FIGS. 16 and 17, several of the assembly 300 can bearranged together to create a hydrogen storage system 350. The housingof the assembly 300 defines at top profile that is generally square orrectangular in shape, thereby enabling a relatively close-packedarrangement.

To prepare the wafers 118, 218, 318, a plate or a disc of the metalhydride producing substrate material (e.g., a magnesium-based alloy) canbe provided, and the de-activation material (e.g. a layer of nickel) canbe electrodeposited onto the plate/disc. Prior to electrodeposition,outer surfaces of the plate/disc can be prepared, including, forexample, acetone-cleaning by ultrasonic techniques, and then keptimmersed in distilled water at room temperature. Suitable electrolyteand plating parameters can be selected to electrodeposit, for example,the layer of nickel to a thickness of between 0.5 and 1.5 μm, or about 1μm, and with a surface roughness of about 1 μm R_(a) or less. In someexamples, a nickel sulfamate plating solution can be used withelectroplating conditions of about 40 to 60° C. solution temperature, acurrent density of about 2 to 25 A/dm² and a pH of about 3.5 to 4.5.

The hydrogen storage assemblies 100, 200, 300 can be used for storinghydrogen gas for use in transportation or other commercial applications.The hydrogen storage assemblies 100, 200, 300 can be used potentiallyfor indoor vehicles as fuel or in confined spaces where insufficient airmay pose a problem.

In use, heat can be transferred to the wafers 118, 218, 318 to attain anoperating temperature suitable for hydrogen charging on the reactionsurfaces 120, 220, 320, which can be a moderate or low temperature ofabout 250° C. or less. A hydrogen-rich carrier fluid can be flowed overthe wafers 118, 218, 318 so as to charge hydrogen on the reactionsurfaces 120, 220, 320 and thereby store hydrogen. In some examples, thehydrogen-rich carrier fluid can have more than 80% hydrogen gas mixedwith an inert gas (e.g., argon or helium). The carrier fluid can bedelivered to the wafers 118, 218, 318 at a relatively low exposurepressure of about 10 Torr or less. A second carrier fluid can be flowedover the wafers 118, 218, 318 to discharge hydrogen from the reactionsurfaces 120, 220, 320 and thereby release hydrogen. In some examples,the second carrier fluid that gathers the hydrogen being discharged canbe an inert gas.

While the above description provides examples of one or more apparatusesor methods, it will be appreciated that other apparatuses or methods maybe within the scope of the accompanying claims.

We claim:
 1. A hydrogen storage assembly, comprising: a housing; acentral electrical busbar supported by the housing and positionedgenerally along a central axis of the assembly; at least one waferformed of a substrate material that produces metal hydride when exposedto a hydrogen-rich carrier fluid, the at least one wafer supported bythe housing and arranged so that the hydrogen-rich carrier fluid canflow over a reaction surface of the at least one wafer; and at least oneheating element arranged to transfer heat to the at least one wafer toattain an operating temperature suitable for hydrogen charging on thereaction surface, the at least one heating element comprising aplurality of electrical heating elements connected to and spaced aboutthe central electrical busbar.
 2. The hydrogen storage assembly of claim1, wherein the at least one wafer comprises a plurality of monolithicplate wafers spaced apart about the central axis.
 3. The hydrogenstorage assembly of claim 2, wherein each of the electrical heatingelements is received in a respective sleeve and positioned between thereaction surfaces of adjacent ones of the plate wafers to heat the platewafers by thermal radiation.
 4. The hydrogen storage assembly of claim3, wherein each of the electrical heating elements is generallyequidistant between the reaction surfaces of the adjacent ones of theplate wafers.
 5. The hydrogen storage assembly of claim 2, comprising ade-activation material on the reaction surface for inhibiting formationof surface oxide that impedes hydrogen absorption during charging andhydrogen desorption during discharging.
 6. The hydrogen storage assemblyof claim 5, wherein the substrate material is a magnesium-based alloy,and the de-activation material is a layer of nickel deposited on thereaction surface.
 7. The hydrogen storage assembly of claim 6, whereinthe layer of nickel has a thickness of between 0.5 and 1.5 μm.
 8. Thehydrogen storage assembly of claim 6, wherein the layer of nickel has asurface roughness of about 1 μm R_(a) or less.
 9. The hydrogen storageassembly of claim 2, wherein each of the plate wafers is suspendedgenerally radially between respective inner and outer supports of thehousing.
 10. The hydrogen storage assembly of claim 9, wherein opposingedges of each of the plate wafers is received in an outwardly facinggroove of the respective inner support and an inwardly facing groove ofthe respective outer support.
 11. The hydrogen storage assembly of claim2, wherein the housing comprises at least one sidewall and at least oneend cap, each having passages permitting flow of the hydrogen-richcarrier fluid over the plate wafers.
 12. The hydrogen storage assemblyof claim 11, wherein the at least one sidewall and at least one end capdefine a top profile of the hydrogen storage assembly that is generallyround or hexagonal in shape.
 13. A method of storing hydrogen,comprising: providing a hydrogen storage assembly comprising a pluralityof wafers formed of a substrate material that produces metal hydridewhen exposed to a hydrogen-rich carrier fluid, the plurality of waferseach comprising a reaction surface and a de-activation material on thereaction surface; transferring heat to the plurality of wafers to attainan operating temperature suitable for hydrogen charging on the reactionsurfaces; and flowing the hydrogen-rich carrier fluid over the pluralityof wafers so as to charge hydrogen on the reaction surfaces, therebystoring hydrogen in the hydrogen storage assembly.
 14. The method ofclaim 13, wherein the de-activation material on the reaction surfacesinhibits formation of surface oxide that impedes hydrogen absorptionduring charging and hydrogen desorption during discharging.
 15. Themethod of claim 14, wherein the substrate material is a magnesium-basedalloy, and the de-activation material is a layer of nickel deposited onthe reaction surfaces.
 16. The method of claim 13, comprisingmaintaining the operating temperature at about 250° C. or less.
 17. Themethod of claim 13, wherein the step of flowing comprises delivering thehydrogen-rich carrier fluid to the at least one wafer at an exposurepressure of about 10 Torr or less.
 18. The method of claim 13,comprising, after the step of flowing, flowing a second carrier fluidover the plurality of wafers to discharge hydrogen from the reactionsurfaces, thereby releasing hydrogen from the hydrogen storage assembly.19. The method of claim 13, wherein the step of heating comprisesheating the plurality of wafers with at least one electrical heatingelement.
 20. The method of claim 19, wherein the step of heatingcomprises heating the plurality of wafers by thermal radiation.
 21. Themethod of claim 20, wherein the plurality of wafers comprises aplurality of monolithic plate wafers, and further comprising arrangingthe at least one electrical heating element between adjacent ones of theplate wafers.
 22. The method of claim 19, wherein the step of heatingcomprises heating the plurality of wafers by thermal conduction.
 23. Themethod of claim 22, wherein the plurality of wafers comprises aplurality of monolithic disc wafers in at least one stacked arrangement,each of the disc wafers comprising a central hole, and furthercomprising arranging the at least one electrical heating elementextending through the central holes of at least a portion of the discwafers.